I'm wondering what would be a 'sensible' track gradient?
I'm looking to work in N-Gauge with possibly G Farish or Dapol steam locos with, maybe, 4 carriages. Possibly also a tank engine with goods trucks.
I would refer you to cs.trains.com/mrr/f/88/t/1030.aspx but also suggest 2% is optimal. Reducing the load the engine is required to pull then 4% to 5% is used on some layouts. Other factors to consider: 1) the number of drive wheels on the engine; 2) the length of the run of track and; 3) is the grade straight or curved?
1:72! Hmm, that seems conservative. It depends on those other factors of course. For example if you were to use the elevation to loop the track around to cross over itself then you need to factor in the height of the tallest cars at 1-23/32" * (any double-stack container cars on your layout?) then add to that roadbed and trestle/tunnel structure that could require a total of 2-1/4" or more. Suppose you work with a 2.5% grade or 1:36 (twice as steep as you were quoted) and wanted to know how much track would be needed to gain the height to loop around and crossover. For every inch gained in height of the track the track needs to run 36 inches. (2.54 cm needs 91 cm.). So a 2.25 inch rise needs 81 inches. Each additional 1/4" (or .635 cm) increase needed in the height of the upper loop will add 9" (or 23 cm.) of more track. I think that is a handy guide when starting a layout. *https://www.thespruce.com/minimum-vertical-clearances-model-trains-scale-2381889
I rechecked the Peco Track Plans book, and it mentions 1:36, not 1:72.
But, thank you for the links, they're very useful.
No plans for double height rolling stock, either containers or continental trains.